1. Field of the Invention
The present invention relates to an inspection method for a circuit substrate, and more particularly to an inspection method for inspecting electrical properties of a circuit substrate having a multilayered structure, by controlling inspection environments so that dew forms on a surface of the circuit substrate and detecting change of states of the dew to thereby determine variation of a thermal capacity of a conductor.
2. Description of the Related Art
A multilayered circuit substrate is structured by accumulating a plurality of circuit substrates and interconnecting circuit patterns of the respective circuit substrates through contacts or vias. Compared to other general circuit substrates which include the circuit pattern on one or both sides, such a multilayered circuit substrate is capable of achieving a highly integrated circuit in a compact size.
FIG. 1 and FIG. 2 are views showing a general multilayered circuit substrate.
As shown in the drawings, the multilayered circuit substrate comprises pattern layers 20 each including circuit patterns 22, 24 and 26, and insulation layers 10 for insulation from and adhesion to the pattern layers 20, the pattern layers 20 and the insulation layers 10 which are accumulated in an alternate order.
In order to inspect whether there is any disconnection and a short circuit of the circuit patterns 22, 24 and 26 of the circuit substrate, electric currents are applied from one end of each of the circuit patterns 22, 24 and 26 one by one and voltages are measured at the other end of the circuit patterns 22, 24 and 26 as shown in FIG. 1. Otherwise, the disconnection and the short circuit may be detected by tracking a conductor using a microscope.
It is noted that the above explanation is related to the background art of the present invention, not merely to a conventional art.
Here, at least two probes are necessitated to detect the disconnection and the short circuit for one circuit pattern on the circuit substrate. Accordingly, a lot of probes are required, thereby increasing the prime cost and the inspection time.
Furthermore, in the multilayered circuit substrate, it may be impossible to detect the disconnection and the short circuit if any defect occurs at the contact or the via (section A in FIG. 3) for connecting the circuit pattern 22 disposed in an inner layer with the circuit pattern 24 disposed in an outer layer 3. Also, in case of a micro via or the inner-layer circuit pattern 22, the disconnection and the short circuit may not be detected by measuring the voltage at the outer-layer circuit pattern 24 using the probe. In addition, it may be impossible to detect the disconnection and the short circuit of the circuit pattern 26 through the microscope.